In a neutralization reaction, the moles of acid must equal the moles of base. The reaction between hydrochloric acid HCl and sodium hydroxide NaOH is as follows:HCl + NaOH NaCl + H2OTo find the volume of 0.2 M HCl needed to react with 25 mL of 0.1 M NaOH, we can use the formula:moles of acid = moles of baseMolarity acid Volume acid = Molarity base Volume base Let V be the volume of HCl needed:0.2 M V = 0.1 M 25 mLV = 0.1 M 25 mL / 0.2 MV = 12.5 mLSo, 12.5 mL of 0.2 M hydrochloric acid is needed to completely react with 25 mL of 0.1 M sodium hydroxide in a neutralization reaction.